You're actually very close! Your cash flow timeline for the first project is correct. The main things to watch are how Excel handles Year 0 and how the second investment option differs from the first.
Let's work through both projects step by step.
1. Cash Flows for the Retail Strip Mall
Year 0: -$8,000,000 (purchase of land)
Year 1: -$3,500,000 (construction costs)
Year 2: +$750,000 (rental profit)
Year 3: +$750,000 (rental profit)
Year 4: +$750,000 (rental profit)
Year 4: +$13,000,000 (sale of completed strip mall)
Since Year 4 has two inflows, combine them when calculating NPV:
Year 4 = $750,000 + $13,000,000 = $13,750,000
2. Calculate NPV Using an 8% Discount Rate
Net Present Value (NPV) measures the value today of all future cash flows, minus the initial investment.
The formula is:
NPV = CF0 + CF1/(1+r) + CF2/(1+r)^2 + CF3/(1+r)^3 + CF4/(1+r)^4
Where:
CF = Cash flow in each year
r = Discount rate = 0.08
Substitute the cash flows:
NPV = -8,000,000 - 3,500,000/(1.08) + 750,000/(1.08)^2 + 750,000/(1.08)^3 + 13,750,000/(1.08)^4
Notice that we do not discount the initial $8 million because it is paid today.
How to Calculate This in Excel
Enter the following:
A1: Year
B1: Cash Flow
A2: 0
B2: -8000000
A3: 1
B3: -3500000
A4: 2
B4: 750000
A5: 3
B5: 750000
A6: 4
B6: 13750000
Then enter this formula into an empty cell:
=NPV(8%,B3)+B2
Important: Excel's NPV function assumes the first cash flow in its range occurs at the end of Year 1, not today. That is why we add the Year 0 cash flow separately.
3. Should You Undertake the Project?
The NPV rule is:
If NPV > 0, accept the project because it is expected to earn more than the required return.
If NPV < 0, reject the project because it is expected to earn less than the required return.
If NPV = 0, the project is expected to earn exactly the required return.
A positive NPV means the investment is financially worthwhile under the assumptions given.
4. Compare With Buying and Holding the Vacant Land
This is where your second calculation needs a correction.
The alternative is to purchase the land today, hold it for four years, and sell the vacant land for $11 million.
There is no construction and no rental income.
Therefore, the cash flows are:
Year 0: -$8,000,000 (purchase of land)
Year 1: $0
Year 2: $0
Year 3: $0
Year 4: +$11,000,000 (sale of vacant land)
The NPV formula becomes:
NPV = -8,000,000 + 11,000,000/(1.08)^4
In Excel, enter:
=NPV(8%,0,0,0,11000000)-8000000
The mistake in your original second calculation was including construction expenses and rental income even though those cash flows would not occur if you simply held the land.